Position sensing a location pin in a welding electrode

ABSTRACT

An apparatus includes a housing, a pin, a mechanism and a sensor. The housing is configured to receive a weld head. The pin is configured to move linearly relative to said housing. The mechanism is configured to convert a position of said pin into a displacement. The sensor is configured to generate a value representative of said position of said pin based on said displacement.

This application relates to U.S. Ser. No. 15/886,047, filed Feb. 1,2018, now U.S. Pat. No. 10,639,738, which relates to U.S. Ser. No.15/692,074, filed Aug. 31, 2017, now U.S. Pat. No. 9,914,181, whichrelates to U.S. Ser. No. 14/867,600, filed Sep. 28, 2015, now U.S. Pat.No. 9,789,562, which are incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to resistance welding generally and, moreparticularly, to a method and/or architecture for position sensing alocation pin in a welding electrode.

BACKGROUND OF THE INVENTION

Detecting a proper orientation of a weld fastener before applying awelding current is an issue in conventional welding assemblies. Amis-orientated or incorrect weld fastener can cause destruction of thewelding electrodes, destruction of the weld fastener and destruction ofthe weld tooling. Any such destruction causes delays in production andincurs an expense in replacing the destroyed parts. Welding with thewrong fastener, or welding with the correct fastener but in the wrongorientation, results in rejections of the welded fasteners, failures inthe welded fasteners in service and rework to replace the mis-weldedfasteners.

It would be desirable to implement position sensing a location pin in awelding electrode.

SUMMARY OF THE INVENTION

The present invention concerns an apparatus including a housing, a pin,a mechanism and a sensor. The housing is configured to receive a weldhead. The pin is configured to move linearly relative to said housing.The mechanism is configured to convert a position of said pin into adisplacement. The sensor is configured to generate a valuerepresentative of said position of said pin based on said displacement.

The objects, features and advantages of the present invention includeproviding position sensing a location pin in a welding electrode thatmay (i) monitor an orientation of a weld part, (ii) monitor apresence/absence of the weld part, (iii) sense a position of a locationpin in a way immune to electromagnetic fields generated during thewelding process, (iv) incorporate inexpensive monitoring components, (v)replicate a height of conventional electrodes without the positionsensing, (vi) incorporate a limit switch, (vii) incorporate a voltagedetector, (viii) incorporate a visual indicator, (ix) incorporate anelectrical angle sensor, (x) incorporate a mechanical angle sensor, (xi)incorporate an optical angle sensor, (xii) incorporate a pneumatic anglesensor, (xiii) provide ease of maintenance and/or (xiv) easily adapt toexisting weld assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will be apparent from the following detailed description andthe appended claims and drawings in which:

FIG. 1 is a cross-sectional exposed view of an apparatus in accordancewith a preferred embodiment of the present invention;

FIG. 2 is another cross-sectional view of the apparatus;

FIG. 3 is a cross-sectional view of another apparatus;

FIG. 4 is a diagram of an electro-mechanical angle sensor;

FIG. 5 is a cross-sectional view of an optical angle sensor;

FIG. 6 is a detailed diagram of the optical angle sensor;

FIG. 7 is a diagram of a pneumatic angle sensor;

FIG. 8 is a cross-sectional view of another apparatus;

FIG. 9 is a cross-sectional view of a load position;

FIG. 10 is a cross-sectional view before welding;

FIG. 11 is a cross-sectional view after the welding;

FIG. 12 is a cross-sectional view with an upside down fastener;

FIG. 13 is a perspective view of another apparatus; and

FIG. 14 is a cross-sectional view of still another apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments of the present invention may provide one or moremonitoring techniques of a position, an orientation and/or an absence ofa part to be welded before welding begins. The monitoring techniques aregenerally immune to electromagnetic fields generated by a weldingcurrent applied by a welding electrode to the part to be welded. Awelding electrode incorporating the monitoring techniques may have aheight matching or similar to that of existing welding electrodeswithout the monitoring techniques. Where incorporated into one of a pairof welding electrodes (e.g., a lower and/or stationary electrode), thewelding electrodes may be easily adapted to existing welding machinesand provide ease of maintenance.

A location pin of the welding electrode may move linearly in a housingto determine an orientation and/or absence of the part to be welded. Aposition of the location pin may be monitored (or sensed) by convertingthe position of the location pin into an angular position and measuringthe angular position. The monitoring techniques may incorporate low-costsensors. The sensors generally include, but are not limited to, a limitswitch, a voltage detector, a visual indicator, an electrical anglesensor, a mechanical angle sensor, an optical angle sensor and/or apneumatic angle sensor. Other sensors that measure a rotation of a shaftmay be implemented to meet the criteria of a particular designapplication.

Referring to FIG. 1, a cross-sectional exposed view of an exampleimplementation of an apparatus 100 is shown in accordance with apreferred embodiment of the present invention. The apparatus (or system)100 may implement a welding electrode. The apparatus 100 may beconfigured to weld a fastener (or part) 90 to an object (or component)92. The welding may be achieved by electrical resistance welding.

The apparatus 100 generally comprises a housing (or assembly) 102, alocation pin (or assembly) 104, a cavity (or bore) 106, a port (or bore)108, a spring (or assembly) 110, a rotary lever (or arm) 112, a shaft(or rod) 114, a weld head (or electrode) 116, a rotary indicator (seeFIG. 2) 118 and an encoder (or monitor) 120. In operation, the fastener90 and the object 92 are brought into contact with the weld head 116 atan end of the housing 102. The location pin 104 is generally received inan opening of the fastener 90 and an opening of the object 92. A lineardistance that the location pin 104 travels into the opening of thefastener 90 generally indicates if the fastener 90 is selectively (oralternatively) in a proper orientation, an improper orientation (e.g.,upside down), missing and/or is an incorrect part.

The location pin 104 may be pushed (or biased) toward the fastener 90 byair pressure created in the cavity 106 through the port 108 and/or bythe spring 110. As the assembly 100 and the fastener 90/object 92 arebrought together, the location pin 104 generally contacts the fastener90. A force created between the fastener 90 and the location pin 104 maycause the location pin 104 to move into the housing 102 and compress thespring 110. The movement may stop when the weld head 116 contacts theobject 92. The weld head 116 generally conveys the welding current tothe object 92.

The rotary lever 112 is generally disposed between the location pin 104and the spring 110. The linear motion of the location pin 104 may beconverted (or translated) into an angular motion of the rotary lever 112about the shaft 114. A center of rotation of the shaft 114 is generallyoffset from a centerline of the location pin 104 (e.g., offset to theleft in the figure). The sensor 120 may measure an angle (e.g., anabsolute angle or a relative angle) of the shaft 114 in reference to thehousing 102. An angle value of the measured angle of the shaft 114 isgenerally proportional to a distance (e.g., Z) traveled by the locationpin 104 in reference to the housing 102 while the fastener 90/the object92 are moved from an initially-contacting (or load) position to awelding position. The distance (or position) Z that the location pin 104travels may be used to determine if the welding process may be allowed(e.g., a proper fastener 90 in a proper orientation) or should be denied(e.g., wrong fastener, missing fastener, incorrect orientation, and/orany other error).

Referring to FIG. 2, another cross-sectional view of the apparatus 100is shown. A combination of the rotary indicator 118 and the encoder 120may form a sensor (or detector) 122. The sensor 122 may be incommunication with a circuit 124 via one or more electrical signals.

The rotary indicator 118 may be coupled to the shaft 114. In variousembodiments, the coupling may be a direct connection or an indirectconnection between the rotary indicator 118 and the shaft 114. Thecoupling generally causes the rotation of the shaft 114 to be conveyedto the rotary indicator 118. The angular position of the rotaryindicator 118 relative to the housing 102 may be identical to theangular position of the shaft 114. The encoder 120 may be mounted on thehousing 102 in alignment with the rotary indicator 118.

In some embodiments, the rotary indicator 118 may be implemented as apositioning element. For example, the rotary indicator 118 may be apositioning element (e.g., part number P1-Ri-SR14, available from TurckInc., Minneapolis, Minn.) for inductive angle sensors. In someembodiments, the encoder 120 may be implemented as an inductive anglesensor (e.g., part number Ri30-P2-QR14, available from Truck Inc.) Invarious embodiments, the rotary indicator 118 and the encoder 120 may bearranged in a non-contact configuration.

The sensor 122 generally provides an oscillator circuit coupling betweena transducer in the encoder 120 and a sensor in the rotary indicator118. The oscillator circuit coupling may be immune to electromagneticinterference, such as the electromagnetic fields generated during thewelding process. The sensor 122 may generate an analog electrical signalproportional to an angle of the rotary indicator 118 relative to theencoder 120. The analog electrical signal may be digitized in thecircuit 124 to a finite resolution (e.g., 12 bits). At 12-bitsresolution, the circuit 124 may monitor an angle value of the shaft 114to a few hundredths of a degree (e.g., ≤0.09 degrees). Additionaldetails of the sensor 122 may be found in datasheet “Inductive AngleSensor With Analog Output”, Ri30P2-QR14-LiU5X2-0,3-RS4, by Turck Inc.,which is hereby incorporated by reference in its entirety. Other typesof electrical angle sensors may be implemented to meet the criteria of aparticular design application.

The circuit 124 may implement a detector circuit. The circuit 124 isgenerally operational to measure the electrical signal generated by thesensor 122. Based on the measurement, the circuit 124 may provide statusof the location pin 104 position to a weld control circuit (not shown).The weld control circuit generally controls the welding current appliedto the weld head 116. The status may include, but is not limited to, aproper orientation of the fastener 90, an incorrect orientation of thefastener 90, the fastener 90 is missing and/or an incorrect fastener isdetected. For example, the angular position measured by the sensor 122may be translated in the circuit 124 to a linear position of thelocation pin 104. Where the location pin 104 is in a “correctorientation” position range, the circuit 124 may signal the weld controlcircuit that the fastener 90/object 92 are ready to weld. Where thelocation pin 104 is in an “incorrect orientation” position range, thecircuit 124 may signal the weld control circuit that the fastener 90 ispresent and in the wrong orientation. Where the location pin 104 is inone or more possible “wrong part” position ranges, the circuit 124 maysignal the weld control circuit that an incorrect fastener is loaded.Where the location pin 104 is in a “missing” position range, the circuit124 may signal the weld control circuit that the fastener 90 and/orobject 92 is missing. Other position ranges of the location pin 104 maybe implemented to meet the design criteria of a particular application.

Referring to FIG. 3, a cross-sectional view of an example implementationof an apparatus 100 a is shown. The apparatus 100 a may be a variationof the apparatus 100. The apparatus 100 a generally includes the housing102, a spring (or assembly) 110 a, a shaft (or rod) 114 a and a sensor(or detector) 122 a. The sensor 122 a may be in electrical communicationwith a circuit 124 a. The spring 110 a (e.g., a rotary spring) may be avariation of the spring 110. The shaft 114 a may be a variation of theshaft 114. The sensor 122 a may be a variation of the sensor 122. Thecircuit 124 a may be a variation of the circuit 124. Other elements ofthe apparatus 100 may be included in the apparatus 100 a.

The sensor 122 a may implement an electrical angle sensor. The sensor122 a may be operational to convert the angular position of the shaft114 a into an angle value. The angle value may be presented in one ormore electrical signals to the circuit 124 a. The shaft 114 a may belonger than the shaft 114. The shaft 114 a may extend outside thehousing 102 and into the sensor 122 a. The circuit 124 a may beoperational to measure the angle value measured by the sensor 122 a. Thecircuit 124 a may be operational to provide the status indications tothe weld control circuit based on the measured angle value, similar tothe circuit 124.

Referring to FIG. 4, a diagram of an example implementation of anelectro-mechanical angle sensor 122 b is shown. The sensor 122 b may bea variation of the sensors 122 and/or 122 a. The sensor 122 b may bemounted to the housing 102. The sensor 122 b may be in electricalcommunication with a circuit 124 b. The circuit 124 b may be a variationof the circuits 124 and/or 124 a.

The sensor 122 b generally comprises a wheel (or disk) 130, an arm (orlever) 132, a detent 134 in the wheel 130, a contact switch (or relay)136 and a latch (or limit switch) 138. The wheel 130 may be coupled,indirectly connected, or directly connected to the shaft 114 a. Thecircuit 124 b may be operational to provide the status indications tothe weld control circuit based on the measured angle value, similar tothe circuit 124.

As the location pin 104 is pushed into the housing 102, the wheel 130may be turned by the shaft 114 a. In some embodiments, the arm 132 maybe designed to press the contact switch 136 if the distance traveled bythe location pin 104 indicates a present and properly oriented fastener90. The circuit 124 b may electrically sense a change in the contactswitch 136 from unpressed to pressed. While the contact switch 136 ispressed, the circuit 124 b may communicate to the weld control circuitthat the fastener 90, the object 92 and the weld head 116 combinationare in a correct orientation to be welded. While the contact switch 136is unpressed, the circuit 124 b may communicate to the weld controlcircuit that at least one of the fastener 90, the object 92 and/or theweld head 116 combination is not ready for the weld process to takeplace.

A length from the center of rotation of the shaft 114 a to an outer endof the arm 132 may be greater than a length of the lever 112 (FIG. 1).The longer length of the arm 132 may provide a mechanical amplificationof the distance Z that the location pin 104 is moved. A small movementof the location pin 104 may be translated into a larger linear movementof the contact switch 136 allowing for a more precise sensing of wherethe location pin 104 is positioned.

In other embodiments, the detent 134 and the latch 138 may be designedsuch that the detent 134 and the latch 138 are aligned with each otherwhen the fastener 90, the object 92 and the weld head 116 combinationare in a correct orientation to be welded. The circuit 124 b may beconfigured to electrically monitor the latch 138 to detect an alignedcondition and a not align condition between the detent 134 and the latch136. When aligned, the circuit 124 b may communicate to the weld controlcircuit that the welding process may take place. The circuit 124 b maybe configured to treat a non-aligned condition between the detent 134and the latch 138 as an indication that at least one of the fastener 90,the object 92 and/or the weld head 116 combination is not ready for theweld process to take place.

Referring to FIG. 5, a cross-sectional view of an example implementationof an optical angle sensor 122 c is shown. The sensor 122 c may be avariation of the sensors 122, 122 a and/or 122 b. The sensor 122 c maybe mounted to the housing 102. The sensor 122 c may be in electricalcommunication with a circuit 124 c. The circuit 124 c may be a variationof the circuits 124, 124 a and/or 124 b.

The sensor 122 c may be directly or indirectly coupled or connected tothe shaft 114 a. An electrical signal generated by the sensor 122 c maybe proportional to an angle (absolute or relative) of the shaft 114 a.The electrical signal generated by the sensor 122 c may be received bythe circuit 124 c. The circuit 124 c may examine the signal to determineif the fastener 90, the object 92 and the weld head 116 are properlyaligned for the welding process to begin. Based on the angle valuereceived in the electrical signal, the circuit 124 c may determine thatone or more of the fastener 90, the object 92 and/or the weld head 116are not ready for welding. The circuit 124 c may report the ready/notready/missing part/wrong part determination to the weld control circuit.The circuit 124 c may be operational to provide the status indicationsto the weld control circuit based on the measured angle value, similarto the circuit 124.

Referring to FIG. 6, a detailed diagram of an example implementation ofthe sensor 122 c is shown. The sensor 122 c generally comprises anextension (or wheel) 140, a shutter (or block) 142, a light source 144that shines a light beam 146 toward a light sensor 150. The shutter 142may be aligned along an outer edge of the extension 140 to prevent thelight beam 146 from reaching the light sensor 150 at some angles (asshown). The shutter 142 may permit the light beam 146 to reach the lightsensor 150 along a path 148 at other angles. The extension 140 may becoupled (or indirectly connected or directly connected) to the shaft 114a.

The circuit 124 c may receive an electrical signal from the light sensor150. The electrical signal may indicate that the light bean 146 haseither reached the sensor 150 or is blocked by the shutter 142. Beforethe location pin 104 engages the fastener 90, the light beam 146 mayreach the light sensor 150. The circuit 124 c may monitor the lightsensor 150 and communicate to the weld control circuit that the weldingprocess should be inhibited. Where the location pin 104, the fastener 90and the object 92 are present and properly aligned, the extension 140may rotate the shutter 142 into the light beam 146 (as shown) to preventthe light beam 146 from reaching the light sensor 150. The circuit 124 cmay sense the change in the electrical signal generated by the now-darklight sensor 150 and communicate to the weld control circuit that thewelding process may proceed. If the location pin 104 travels too far,the light beam 146 may become unblocked by the shutter 142. The lightsensor 150 may convey the illumination to the circuit 124 c. The circuit124 c may communicate to the weld control circuit that something iswrong with the faster 90, the object 92 and/or the location pin 104. Theweld control circuit may inhibit the welding process in such situations.In various embodiments, the shutter 142 may be configured such that thelight bean 146 reaches the light sensor 150 only when the faster 90, theobject 92 and the location pin 104 are properly positioned for welding,and block the light beam 146 otherwise.

A length from the center of rotation of the shaft 114 a to a point onthe shutter 142 that engages the light beam 146 may be greater than alength of the lever 112 (FIG. 1). The longer length may provide amechanical amplification of the distance Z that the location pin 104 ismoved. A small movement of the location pin 104 may be translated into alarger angular movement of the shutter 142 allowing for a more precisesensing of where the location pin 104 is positioned.

The extension 140 may include markings 152. The markings 152 may providea visual indication of the position of the location pin 104 relative tothe housing 102. The visual indication may be used by an operator of thewelding assembly to verify that the fastener 90, the object 92 and theweld head 116 are ready or not ready for the welding process to begin.

Referring to FIG. 7, a diagram of an example implementation of apneumatic angle sensor 122 d is shown. The sensor 122 d may be avariation of the sensors 122, 122 a, 122 b and/or 122 c. The sensor 122d may be mounted to the housing 102. The sensor 122 d may be inelectrical communication with a circuit 124 d. The circuit 124 d may bea variation of the circuits 124, 124 a, 124 b and/or 124 c.

The sensor 122 d generally comprises a wheel (or disk) 160, a tube (orbore) 162 through the wheel 160, an input tube (or pipe) 164, an outputtube (or pipe) 166 and a pressure sensor 168. An open end of the inputtube 164 may receive a pressurized fluid or gas. The pressure sensor 168may generate a pressure value proportional to a pressure in the outputtube 166. The pressure value may be conveyed from the pressure sensor168 to the circuit 124 d in an electrical signal. The circuit 124 d maybe operational to provide the status indications to the weld controlcircuit based on the measured pressure value, similar to the circuit124.

Before the location pin 104 engages the fastener 90, the tube 162 mayblock the pressure in the input tube 164 from reaching the pressuresensor 168 via the output tube 166. The circuit 124 d may monitor thepressure sensor 168 and communicate to the weld control circuit that thewelding process should be inhibited. Where the location pin 104, thefastener 90 and the object 92 are present and properly aligned, thewheel 160 may rotate the tube 162 into alignment with the input tube 164and the output tube 166. The rotation effectively opens a valve formedby the wheel 160 and the tubes 162, 164 and 166. The circuit 124 d maysense the change in the pressure value in the electrical signalgenerated by the pressure sensor 168 and communicate to the weld controlcircuit that the welding process may proceed. If the location pin 104travels too far, the tube 162 may rotate out of alignment with the tubes164 and 166. The pressure sensor 168 may convey the reduced pressure tothe circuit 124 d. The circuit 124 d may communicate to the weld controlcircuit that something is wrong with the faster 90, the object 92 and/orthe location pin 104. The weld control circuit may inhibit the weldingprocess in such situations.

Referring to FIG. 8, a cross-sectional view of an example implementationof an apparatus 100 b is shown. The apparatus 100 b may be a variationof the apparatus 100 and/or the apparatus 100 a. The apparatus 100 b maybe used to weld a weld stud (or part) 90 a to the object 92. To accountfor different geometries between the weld stud 90 a and the fastener 90,the apparatus 100 b may include a push pin 104 a in place of thelocation pin 104. Operation of the apparatus 100 b may be similar tothat of the apparatus 100 and/or the apparatus 100 a. Other elements ofthe apparatus 100 and/or the apparatus 100 a may be included in theapparatus 100 b.

Referring to FIG. 9, a cross-sectional view of the fastener 90 in a loadposition is shown. In the load position, the location pin 104 may bepushed (or biased) to a maximum distance out of the housing 102. Thefastener 90, if present, may be in contact with the location pin 104 butdoes not apply any force to the location pin 104. If the fastener 90 ismissing, the location pin 104 may also be pushed (or biased) to themaximum distance out of the housing 102. In the load position, thesensor 122 (or 122 a, 122 b, 122 c or 122 d) may be monitored by therespective circuit 124 (or 124 a, 124 b, 124 c or 124 d). The circuit124 may report to the weld control circuit that the welding processshould be inhibited.

Referring to FIG. 10, a cross-sectional view before welding is shown.The fastener 90 may be in contact with the object 92. The location pin104 may be moved a predetermined (or anticipated) distance into thehousing 102. In the before welding position, the sensor 122 (or 122 a,122 b, 122 c or 122 d) may be monitored by the respective circuit 124(or 124 a, 124 b, 124 c or 124 d). The circuit 124 may report to theweld control circuit that the welding process may begin.

Referring to FIG. 11, a cross-sectional view after the welding is shown.The fastener 90 may move slightly closer to the object 92 as protrusionson a bottom of the fastener 90 melt and weld the fastener 90 to theobject 92. The location pin 104 may move the slight distance furtherinto the housing 102. In the after welding position, the sensor 122 (or122 a, 122 b, 122 c or 122 d) may be monitored by the respective circuit124 (or 124 a, 124 b, 124 c or 124 d). The circuit 124 may report to theweld control circuit that the welding process was successful.

Referring to FIG. 12, a cross-sectional view with an upside downfastener 90 is shown. Where the fastener 90 is turned upside downrelative to the object 92, the location pin 104 may be moved an improperdistance into the housing 102. The improper distance may be differentfrom the predetermined distance due to a geometry difference on opposingsides of the fastener 90. For example, a top side of the fastener 90(e.g., the side normally facing away from the object 92), may include abeveled inside edge 94 (also see FIG. 11). If the fastener 90 is upsidedown, the beveled inside edge 94 may allow the location pin 104 toprotrude a further distance out of the housing 102 than would normallybe expected. The circuit 124 may monitor the further distance andcommunicate to the weld control circuit to inhibit the welding processbecause the fastener 90 is mis-oriented.

Referring to FIG. 13, a perspective view of an example implementation ofan apparatus 100 c is shown. The apparatus 100 c may be a variation ofthe apparatus 100, the apparatus 100 a and/or the apparatus 100 b. Theapparatus 100 c may be used to weld a fastener 90 (shown) and/or a weldstud 90 a to the object 92. The apparatus 100 c may include one or moresets of gears configured to increase an angular displacement of thesensors 122, 122 a, 122 b, 122 c and/or 122 d to provide better locationmeasurements. Operation of the apparatus 100 c may be similar to that ofthe apparatus 100, the apparatus 100 a and/or the apparatus 100 b.

The apparatus 100 c generally includes the housing 102, the location pin104, a spring (or assembly) 110 b, a rotary lever (or arm) 112 a, theshaft 114 b, a shaft (or rod) 115, multiple gears 117 a-117 b and thesensor 122 (e.g., the rotary indicator 118 and the rotary indicator120). The spring 110 b (e.g., a rotary spring) may be a variation of thespring 110 a. The spring 110 b may be wound around the shaft 115 andanchored at a fixed location (e.g., the shaft 114 b). The rotary lever112 a may be a variation of the rotary lever 112. Other elements of theapparatus 100, the apparatus 100 a and/or the apparatus 100 b may beincluded in the apparatus 100 c.

The rotary lever 112 a may be connected to the shaft 115 at one end andengages the location pin 104 at an opposite end. The linear motion ofthe location pin 104 may be converted (or translated) into an angularmotion of the rotary lever 112 a about the shaft 115. A center ofrotation of the shaft 114 is generally offset from a centerline of thelocation pin 104.

The shaft 114 b and the shaft 115 may be aligned to rotate on parallelaxises. A gear 117 a may be connected to an end of the shaft 114 bopposite the rotary indicator 118. Another gear 117 b may be connectedto an end of the shaft 115. The gears 117 a-117 b may mesh such thatrotation of the gear 117 b causes a rotation of the gear 117 a. A gearratio in a range of 1.4:1 to 1.8:1 (e.g., 1.6:1) may cause the shaft 114a to turn at a faster rate as the shaft 115. Other gear ratios and/ornumbers of gears may be implemented to meet the design criteria of aparticular application.

Referring to FIG. 14, a cross-sectional view of an exampleimplementation of an apparatus 100 d is shown. The apparatus 100 d maybe a variation of the apparatus 100, the apparatus 100 a, the apparatus100 b and/or the apparatus 100 c. The apparatus 100 d may be used toweld a fastener 90 and/or a weld stud 90 a (shown) to the object 92. Theapparatus 100 d may also include one or more sets of gears configured toincrease an angular displacement of the sensors 122, 122 a, 122 b, 122 cand/or 122 d to provide better location measurements. Operation of theapparatus 100 d may be similar to that of the apparatus 100, theapparatus 100 a, the apparatus 100 b and/or the apparatus 100 c.

The apparatus 100 d generally includes the housing 102, a taper feature103, the rotary spring 110 b, the rotary lever 112 a, the shaft 114 b,the shaft 115, the gears 117 a-117 b, the sensor 122, a mount (orbracket) 130, a sensor (or device) 132 and a tube 140. Other elements ofthe apparatus 100, the apparatus 100 a, the apparatus 100 b and/or theapparatus 100 c may be included in the apparatus 100 d.

The taper feature 103 may be located at a bottom of the housing 102. Thetaper feature 103 may have a standard shape that allows the assembly 100d to be mounted on a welding machine. The taper feature 103 may beincluded on any of the assemblies 100, 100 a, 100 b, 100 c and/or 100 d.

The mount 130 may implement a sensor mount. The sensor mount 130 isgenerally configured to hold the sensor 132 in a specified locationrelative to the housing 102.

The sensor 132 may implement a spring loaded sensor. The spring loadedsensor 132 is generally operational to determine when the assembly 100 dhas a specified position relative to the object 92. In variousembodiments, the sensor 132 may aid the weld control circuit todetermine if a weld should proceed or not. If the sensor 132 detects thepresence of the object 92 and the sensor 122 detects a properpositioning of the weld stud 90 a, the welding may be performed. If thesensor 132 detects an improper location of the object 92, the weldingmay be inhibited even though the sensor 122 indicates proper placementof the weld stud 90 a.

The tube 140 may implement a water tube. The water tube 140 may providea flow of cooling water through the housing 102 to aid in drawing heataway from the assembly 100 d. In various embodiments, the tube 140 mayimplement an air tube configured to provide a flow of cooling air (orother gas) through the housing 102 to aid in drawing heat away from theassembly 100 d.

The functions and structures illustrated in the diagrams of FIGS. 1-14may be designed, modeled and simulated using one or more of aconventional general purpose processor, digital computer,microprocessor, microcontroller and/or similar computational machines,programmed according to the teachings of the present specification, aswill be apparent to those skilled in the relevant art(s). Appropriatesoftware, firmware, coding, routines, instructions, opcodes, microcode,and/or program modules may readily be prepared by skilled programmersbased on the teachings of the present disclosure, as will also beapparent to those skilled in the relevant art(s). The software isgenerally embodied in a medium or several media, for example anon-transitory storage media, and may be executed by one or more of theprocessors.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade without departing from the scope of the invention.

1. An apparatus comprising: a housing configured to receive a weld head;a pin configured to move linearly relative to said housing; a mechanismconfigured to convert a position of said pin into a displacement; and asensor configured to generate a value representative of said position ofsaid pin based on said displacement.
 2. The apparatus according to claim1, further comprising a circuit configured to generate a status of saidpin based on said value.
 3. The apparatus according to claim 2, whereinsaid status indicates that a part to be welded is selectively one of ina proper orientation, in an improper orientation, and missing.
 4. Theapparatus according to claim 2, wherein said displacement is an angulardisplacement, and said circuit is further configured to translate saidangular displacement into a linear displacement of said pin.
 5. Theapparatus according to claim 4, wherein said circuit is furtherconfigured to measure a resolution of said angular displacement toapproximately 0.09 degrees.
 6. The apparatus according to claim 1,wherein said sensor is one of a mechanical angle sensor, an opticalangle sensor, and a pneumatic angle sensor.
 7. The apparatus accordingto claim 1, wherein said sensor is further configured to generate anelectrical signal that conveys said value.
 8. The apparatus according toclaim 1, wherein said sensor comprises a visual indicator configured toshow that a part, an object, and said weld head are properly positionedfor a welding process to begin.
 9. The apparatus according to claim 1,wherein said mechanism and said sensor are immune to an electromagneticfield generated by said weld head.
 10. The apparatus according to claim1, wherein said apparatus forms part of a welding electrode.
 11. Amethod for position sensing in a welding electrode, the methodcomprising: converting a position of a pin relative to a housing into adisplacement, wherein said pin is configured to move linearly relativeto said housing; and said housing is configured to receive a weld head;and sensing a value representative of said position of said pin based onsaid displacement.
 12. The method according to claim 11, furthercomprising: generating a status of said pin with a circuit based on saidvalue.
 13. The method according to claim 12, wherein said statusindicates that a part to be welded is selectively one of in a properorientation, in an improper orientation, and missing.
 14. The methodaccording to claim 12, wherein said displacement is an angulardisplacement, and the method further comprises: translating said angulardisplacement into a linear displacement of said pin.
 15. The methodaccording to claim 14, further comprising: measuring a resolution ofsaid angular displacement to approximately 0.09 degrees.
 16. The methodaccording to claim 11, wherein said sensing is one of a mechanical anglesensing, an optical angle sensing, and a pneumatic angle sensing. 17.The method according to claim 11, wherein said sensing includesgenerating an electrical signal that conveys said value.
 18. The methodaccording to claim 11, further comprising: generating a visual indicatorconfigured to show that a part, an object, and said weld head areproperly positioned for a welding process to begin.
 19. The methodaccording to claim 11, wherein a determination of said position isimmune to an electromagnetic field generated by said weld head.
 20. Themethod according to claim 11, wherein said method is performed in saidwelding electrode.